A typical arbor for a hole saw includes an arbor body with a threaded end portion that engages a corresponding threaded aperture in the end plate of the hole saw to secure the hole saw to the arbor. A pilot drill bit is receivable within the threaded end portion of the arbor body and extends through the center of the hole saw. The arbor further includes a drive pin plate that slidably mounts to the arbor body and has a pair of diametrically opposed drive pins that extend into corresponding drive pin holes formed in the end plate of the hole saw to rotatably drive the hole saw. A lock nut is threadedly mounted on the arbor body to prevent disengagement of the drive pins from the hole saw during use.
To mount the hole saw to the arbor, the end plate of the hole saw is threaded onto the threaded end portion such that the hole saw is secured to the arbor body and the drive pin holes are in alignment with the corresponding drive pins of the drive pin plate. Then the lock nut is tightened until the drive pins are fully received by the drive pin holes to secure the arbor to the hole saw. To mount the pilot bit, the bit is inserted into the center hole and secured by tightening a fastener.
One of the drawbacks associated with this type of arbor is that hole saws will lock up on the threads if the drive pin plate disengages from the hole saw during operation, presenting the end user with a difficult and time consuming task of removing the hole saw from the arbor. In many circumstances, the process of removing a locked up hole saw from the arbor permanently damages the arbor, the hole saw or both, necessitating the unwanted expense associated with replacing equipment prematurely.
Another drawback of this type of arbor is that it can be necessary to hold the hole saw in place to maintain alignment of the drive pin holes with the corresponding drive pins while simultaneously tightening the lock nut to avoid rotation of the hole saw that otherwise would prevent the drive pins from entering the drive pin holes. To address this problem, proprietary arbors have been devised that accept corresponding proprietary hole saws specifically designed to make hole saw mounting an easier task. However, the versatility of these arbors is greatly limited because they can only mount the particular manufacturer's proprietary hole saws and are not able to mount standard hole saws. Accordingly, it would be advantageous for such proprietary arbors to accept standard hole saws because they tend to be readily available in the event a proprietary hole saw needs replacing and is not available, or in the event a proprietary hole saw is not available in a desired size and/or cutting configuration.
Still another drawback of this type of arbor is that the process of inserting and removing pilot drill bits frequently requires the end user to manually engage a set screw. To address this issue, proprietary arbors have been devised that secure corresponding proprietary pilot drill bits having shanks configured for securement without the necessity of tools. However, the versatility of these arbors is greatly limited because they can only secure the particular manufacturer's proprietary pilot drill bits, and are not able to secure standard pilot drill bits which are readily available and easily obtainable in the event a proprietary pilot drill bit needs replacing and is not available, or in the event a proprietary pilot drill bit is not available in a desired size and/or drilling configuration. Further, such proprietary arbor and pilot drill bit systems can fail at fully securing the bits inside the arbor and/or can allow the bits to loosen during use causing off-axis wobble, especially at high rotational speeds. Off-axis wobble can cause undesirable vibration of the pilot drill bit that can reduce the drilling life of the bit and/or create an unacceptable degree of inaccuracy during use.
Accordingly, it is an object of the present invention to overcome one or more of the above-described drawbacks and/or disadvantages of the prior art.